Testing system



F. K. Low

TESTING SYSTEM Jan., v 28, 1936.

'7 Sheets-Sheet l Filed Aug. 25, 1934 /NVENTOR By EKLOW @6M ATTORNEY F.K. Low

TESTING SYSTEM jam. 28, Y

Filed Aug.v 25, 1934 7 Sheets-Sheet 2 RUDRINEH lll lllll lllll IllllIllll l h k n n W WVM/TOR F K LW A T TOR/VEY F. K. LOW

Filed Aug. 25, 1934- 7 Sheets-Sheet 3 /NVENTOR By f". K. L ow.

ATTORNEY Jan. 28, 1936. F. K, LOW 2,029,030

TESTING SYSTEM Filed Aug. 25, 1934 7 Sheets-Sheet 4 SECO/VD SENDER LOAD/NVENTOR E K. LOW

ATTORNEY 'FIGS F. K, LOW

TESTING SYSTEM .Fam 28, 1936.

Filed Aug. 25,'1934 7 Sheets-Sheet 5 .mwN

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/N VE N TOR ATTORNEY Jan. 28, 1936.. F. K. LOW

TESTING SYSTEM Filed Aug. 25, 1934 7 Sheets-Sheet 6 /VVENTOR By E K. ow

ATTORNEY N ...al

0.10.. 28, 1936. F. K. Low

TESTING SYSTEM Filed Aug. 25, 1934l '7 Sheets-Sheet 7 @www mw www mmmMmm /NVE/VTOR E K.' L OW IGT@ w w @o m o @@Mwwmo @coswoowo gsm JHM. @V0Wuvw 03m Awa ,EE ooooooooo foo oooooooo ATTORNEY Patented Jan. 28, 1936UNITED STATES PATENT OFFICE TESTING SYSTEM Frank K. Low, Brooklyn,

N. Y., assignor to Bell Telephone Laboratories, Incorporated, New

York, N. Y., a corporati on of New York This invention relates totelephone systems and has for its object; to facilitate the testing ofcertain phases of telephone operation.

AmOng the more phone operation is erated speech currents fortransmitting telephone going to the manual cnice.

routine testing equipment has the greater part of the equipment at thedial oiiice, up to the present, testing the accuracy of suchautomatically spoken designations as trans- While automatic been devisedfor circuit has been by means 0f a manual listening test performed bythe test man. This is a tedious and time consuming task.

According to the present invention means is the accuracy of a series ofover a channel of unknown efclency by providing a duplicate series ofsignals transmitted over a channel of known eiliciency and meansresponsive to diiferences in the signals as transmitted over the twochannels to sound an alarm'.

More specically the invention provides means v for testing the accuracyof transmission of artificially generated words over a particularchannel by transmitting the same words over a control channel andintroducing the words as transmitted over the two channels into areceiving circuit which is sensitive to dierences between the words andrecords such differences.

The specic embodiment of the invention is intended for use in such atesting system as disclosed in Patent 1,624,540, granted April 12, 1927to E. H. Clark and tests call announcer equipment such as disclosed inPatent 1,840,132, granted January 5, 1932 to T. H. Roberts.

The invention will be more clearly understood from a consideration ofthe following description in connection with the drawings in which:

Fig. 1 is a diagrammatic showing of the invention;

Fig. 2 is a diagram indicating the arrangement of Figs. 3 to 8,inclusive;

Fig. 3 shows three speech generating devices;

Fig. 4 shows a portion of the equipment used in distributing the senderload to the speech generators;

Figs. 5 and 6 show portions of the sender to be tested; and

Figs. 7 and 8 show portions of the sender testing equipment.

Fig. 1 shows the fundamental scheme embodying the invention. By means ofsuitable selecting and control apparatus the common speech generator 3D0is connected through the repeating coil 2500 of the circuit under testand repeating coil 803 in the test equipment to one primary winding oftransformer 8I I while the same speech generator is connected throughrepeating coils 700 and 8| 2 in the test circuit to the other primarywinding of transformer 8| I. It is to be noted that the connection ofthe circuit under test to its primary winding is reversed so that thecurrent flow in the two primary windings oppose one another, Thereforeas long as the same speech current flows through the circuit to betested and the duplicate or control circuit built up in the testequipment, the current induced in the secondary SII is so little thateven when amplified by amplifier 8 I9, it is insuicient to aifect therecorder 850. Repeating coil 8I3 and amplifier 8I4 take a small portionof the current received over the circuit under test to indicate to therecorder that the correct number of digits have been received. By theproper adjustment of this auxiliary circuit, inadequate volume of thespeech currents m'ay also be indicated. This slight current drain is, ofcourse, compensated for in the duplicate circuit.

Referring now to the more detailed drawings of Figs. 3 to 8, inclusive,a part of the equipment shown in Fig. 8 has been taken from thedisclosure of the Clark patent above mentioned and this equipment hasbeen given the numbers used in that patent in order to simplifyreference thereto. All numbers in the 800 group in this ligure relate tonew apparatus. Similarly Figs. 5 and 6 show portions of the circuit andapparatus of the Roberts patent and the original numbering has beenretained. For a complete disclosure and description, reference is madeto these two patents. Fig. 4 has been skeletonized from the disclosureof Patent 1,841,197 to R. F. Massonneau et al., granted January 12, 1932which covers switching means for associating the speech generators withthe senders and for guarding against the mutilation of calls because ofspeech failure.

The speech generating machine shown in Fig. 3 comprises fourteen speechgenerating elements, one for each of the numerical digits and one foreach of the four letters used as station designations. Each unitcomprises a light source, a lens for focussing the light on a slit (notshown), a

winding of transformer contacts of cam 22|6, lower Vphotographic recordofthe pronouncement of the corresponding digit, a photoelectric cell fortranslating the record. into electrical speech currents and one or moreampliers to raise the volume of the speech currents to the usualconversational level. The photographic record is mounted on the drum forrotation between the light source andthe photoelectric "cell, drums areci such size that the record of the pronouncement is repeated a numberyof times during each revolution of the drum and the rilm is opaquebetween the pronouncements. These dark spaces permit the Yreenforcementof the drum and are of such length as to simulate the natural intervalbetween spoken words. A cam wheel, carried by the same shaft as operatesan interrupter mechanism which connects ground to a plurality ofsynchronizing leads during the interval when the speech record isVpassing between the light source and the photoelectric cell anddisconnects ground therefrom during the silent interval.

From a consideration ofthe Clark patent-above referred to, it will beapparent that in the testing of sen-ders, it is customary to arrangethe. routine testing equipment so that it will transmit to the sender tobe tested telephone designations indicative of the various types ofoiiice to which the switches controlled by the sender have access. TheYtesting unit also includes equipment which simulates the selectors w Vchare controlled by the sender and which indicates whether the sender isfunctioning correctly.

While no provision is made in the testing equipment of the Clark patentfor testing the senders for calls in the, call announcer class, it is.apparent that such a test may be provided for oy the use of additionalvor intermediate positions on the route switch |100 and the class switch500 and that in general rit would resemble the test simulating a call toan operators desk.

In the manner set forth in that patent the test equipment is associatedwith a sender to be tested by means of armaster selector indicated inthe present disclosure? by brushes 3| I and 3 i |5 and sender selectorbrushes 3 |41 and 3|45. Brush 800 indicates a brush operating with themaster selector brushes and having its terminals strapped to correspondtothe grouping of the senders into loads for the call announcer machine.For a call announcer test, registration and the control of selectionswould take place in the manner described in the Clark patent, afterwhich the fundamental circuitl for trunk test is established between thetest circuit and they sender. When the decoder is released after settingthe selection control registers, relay |42 is operated. .Since a callannouncer class. call is to be handled, class relay 2004 is operated inturn operating relays 2508 and 2|5|, and when the control sequenceswitch vreaches position I5, causing relay 2503 to operate. The trunktest circuit extends from groundl through the lower winding'of relay80|, lower back contactof relay 802,lower left winding repeating coil803, contacts of cam 55|, added to the class sequence switch, outer backcontact of relay 200, contact of cam |508 which is in posi.- tion 8during 2 |00, contacts of cam 3032, key 2404, brush 3| I4,

brush 3|01,`upperback contact of relay 016, contacts of cam 2211, backcontactJ of compensating resistance relay 2024, through compensatingresistance 2043, front contact of compensating resistance relay 2023,backvcontact o-i relay 2302,

ieft winding of re- The the drum, f

' turn operates relay 250| and relay-25| I.

trunk test, back contactof relayY peating coil 2500, lower back contactsof relays 250|, 2502, 240| and 230|, upper back contact of relay 250|,back contact of relay |400, upper winding of polarized relay Y216winding of polarized relay 25|0, upper front contact of relay 2503,

upper left winding of repeating coil 2500, iront' contact of relay 2 5|,back contact of relay 2|52, contacts of cam2209, front contact oi relay||42, back contact of relay 9|6, sender selector brush 3i46, masterselector brush 3| I5, contact of key 2404, contacts of cam 3023,resistance 901, contacts of cam |534, inner back contact of relay 200,contacts of cam 552 (added) upper left winding of repeating coil ,803,upper back contact of relay 802, upper winding of relay 30| to battery.

As set forth in detail in the Roberts patent above referred to, if thefundamental circuit is properly established, the current iiow is in adirection to operate polarized relay 25|0 which in turn operates otherrelays (not shown). In the test circuit relayV 30| operates, in turnoperating relay 804. Relay 804 `connects the synchronizing lead 154 fromthe speech generator over the back contact of relay 300 to and battery.When the synchronizing lead is closed, relay 805 operates closing alocking circuit through the winding of relay 800 which becomes effectiveto operate relay 805 when the synchronizing pulse ends. Similarly relays801 and 808 are operated, relay 808 extending Vthe synchronizing lead tothe winding of relay 802. Relay 802 reverses the connection of relay tothe fundamental circuit thereby releasing relay 25|0 andY Voperatingrelay 2 0 This fundamental circuit is inductively connected by means ofrepeating coil 803 through the normal contacts of key 803, to the rightwinding of repeating coil 8 3 and to the upper contacts of relay 3|0,which in turn extend to the upper vright winding of repeating coil 8H. Acircuit is also prepared in any desirable manner between the leftwindings of repeating coil and the right winding or" repeating coil 2,the left winding of this last repeating coilbeing connected to the lowercontacts of relay 8|0 and thence to the lower right winding ci repeatingcoil 8| I. Relays to 123, inclusive, serve to connect the right windingof repeating coil 100 with the proper one of the speech generatingdrums.

These relays are operated selectively under the control of the test set'registers (not shown) which are, ofcourse, set to the same designationas the registers of the sender. Relays 103, 106, 101,108,1||,1|3 and 1|4are operated under the control of the synchronizing means of the speechgenerating machineY and serve to connect the selecting relays 120 to 121to the registers in-the proper order. All of these relays may welloperate in a manner similar to the selecting and sequence relays of theRoberts patent above mentioned.

In the sender the operation of reiay 2|0| in Relay 25|! locks, openingthe circuit of relay 250| which releases.

In the test circuit, when the synchronizing lead opens, it releasesrelay 802 which restores the direction of the current rlow over thefundamental circuit. Reiay 2|8| thereupon releases and relay 25|0reoperates.

When sequence switch 2200 reached position |5, with relay 2503 operatedto indicate that a call announcer call was to be handled, a circuit wasclosed from battery through the winding of relay 25|3, lower frontcontact of relay 2503 to conductor |004 which extends to thesynchronizing cam of the speech generator of Fig. 3. Relay 25 I3 closesan operating circuitl for relay 25I4 which is therefore operated at eachclosure of the synchronizing cam. When relay 25| 0 reoperates followingthe operation of relay 25|I, relay 25| 5 operates and with relay 25|4operated relay 25|8 operates and locks, in turn operating relay 25I9which connects the right winding of repeating coil 2500 to the contactsof selecting relays 2620 to 2621 which connect the repeating coil to thespeech generators. Relay 25I9 connects condenser 2523 between the leftwindings of the repeating coil 2500 around the windings of relays 2 I 6Iand 25I0 to improve the transmitting quality of the circuit.

As soon as the silent interval ends, the rst digit of the wanted numberwill be pronounced. In the test circuit this voice current will betransmitted through repeating coil 803 and key 809 to repeating coil 8|3and amplifier 8I4, which also recties the current and applies it torelay 8I5 operating it. Relay 8| 5 closes a circuit from ground at itscontact over the back contact of relay 8|8 to the windings of relays 8|0and 150 in parallel. Relay 150 operates disconnecting the synchronizinglead from conductor 154 to prevent the reoperation of relay 802 andextends this lead to the winding of relay 15| which in turn controlsrelay 152. Relay 152 thereupon connects intermittent ground under thecontrol of the call announcer machine to conductor 153. Relay 152 alsocloses a circuit for relay 1| which starts the operation of the testcircuit sequence relays.

Relay 8 I 0 in operating simultaneously connects the speech currentsfrom the sender under test and the speech currents from the test circuitto the right windings of coil 8| As indicated on the drawings theseright windings are so wound that the flux generated by the speechcurrents will oppose one another and therefore if they are identical, aswill be the case if the same digit is being pronounced over the twocircuits, no current will flow through the left winding of coil 8| andrelay 8I1 will not be operated.

Relay 150 in operating also operates relay 8| 6 thereby transferring thecircuit controlled by relay 8I5 to the armature of relay 8I8. Relay 8| 8is operated or non-operated under the control of the test circuitregisters according as a five digit or four digit number is .to bepronounced. Assuming that relay 8 I8 is operated, counting relay 829 isoperated over the back contact of relay 82|, front contacts of relays8|8, 8|6 and 8I5 to ground. Relay 820 locks through the Winding of relay82| and, at the end of the first digit, relay 82| operates transferringthe circuit controlled by relay 8I5 to the contact of relay 823. Thecounting relay pairs 822 and 823, 824 and 825, 826 and 821, 828 and 829operate under the control of relay 8I5 as each successive digit ispronounced. When the last -digit has been pronounced, relay 829 connectsground from conductor 153 over its front contact and the back Contact ofrelay 83| to the winding of relay 830 which operates and locks throughthe Winding of relay 83| and at the end of the synchronizing pulse,relay 83| also operates. When relay 83| operates it connects ground overits outer upper front contact and the back contact of relay 832 toconductor 833 as an indication that the designation has been pronouncedcorrectly. Conductor 833 would be used to advance the test, probably byadvancing sequence switch |500.

If for any digit no pronouncement is received from the sender or thepronouncement has insufiicient volume, relay 8I5 will not operate, relay5 829 will not have been operated when the designation has beencompletely pronounced and no means will exist for operating it, so thatthe test will be blocked. vIf an additional digit is received, or if lvedigits are pronounced where only 10 four should have been, ground willbe connected over the front contacts of relays 8| 5, 8| 6, BIB, 82|,823, 825, 821 and 829 and the back contact of relay 83| to the windingof relay 832 and battery thus disconnecting conductor 833 from thecontact of relay 83| and blocking the test. In addition if a wrong digitis pronounced, sufficient current will ilow in the left winding of coil8II to cause the operation of relay 8|1, which in turn operates relay832 and blocks the test. Relay 832 when operated locks and connectsground to conductor 834 to sound an alarm.

It has been found that the pronouncement of the same digit fromdifferent machines diiers suil'iciently to indicate that a differentdigit has 25 been received. It is, therefore, necessary that the samemachine be used by the testing circuit as is serving the sender undertest. In the patent to Massonneau et al., above mentioned, is disclosedan arrangement for connecting the senders with the call announcermachines. According to that patent three machines are provided and thesenders are divided into two groups or loads so that one machine is freefor adjustment and repairs at all times. Keys are provided for settingup the connection between the machine and the load and automatic meansfor transferring the load, in case any one of the generating drums fail.This equipment is shown in skeleton in Fig. 4, the keys included in box400 and box 40| indicating both the manual and the automatic means forcontrolling the connection. Assume, for example, that relays 4| 3 and42| have been operated. This connects the A load senders, including thesender under test, in multiple to speech generator No. 1, as shown inFig. 3, while the B load senders indicated by the box B in Fig. 4 areconnected in multiple to speech generator No. 2. If speech generator No.2 should fail, the automatic equipment indicated by box 40| wouldrelease relay 42| and operate relay 423 so that both loads would behandled by the same machine. Since the machine No. 3 is not running itcan not be selected automatically. However, an alarm oper- 5 ated at thetime the changeover occurs calls an attendant, and if machine No. 3 isin working condition, he may start it and transfer one of the loads tothat machine. In order to insure that the sender test circuit is servedby the same generator as the sender under test, brush 800 is provided,having its terminals strapped in two groups to correspond to the twoloads. Ground over brush 890 extends over the strapped contactscorresponding to the A load to the lower armatures of relays 4I I, 4|2and 4I3 and over the front contact of the operated relay to the windingof the corresponding test circuit connecting relay 43|, 432 or 433 andbattery. Under the condition rst assumed, that is that relays 4|3 and42| were operated, as long as the sender is testing in the A load, relay433 will be operated, connecting the sender test circuit with generatorNo. l and when the test advances to the senders of the B load, relay 433will release and relay 43| operate to connect the sender test circuit togenerator No. 2. If now, as suggested above, generator No. 2 fail, relay42| is released, and relay 4|3 is operated, relay 43| is likewisereleased and relay 433 operated to similarly transfer the test circuit.

It may be noted that the Vpath for the voice currents through the testcircuit extends through two repeating coils, namely, coils 10!) and SI2in order Vto make the conditions in the duplicate test circuitcorrespond as nearly as possible to the path traversed by the speechcurrents through the sender. Key 809 and receiver 835 permit the testman to make a listening test when desirable.

What is claimed is: Y

1. In a testing system, means for generating signals, a telephonecircuit, means for transmitting a series of said signals to saidtelephone circuit, and means for testing the accuracy of said signals astransmitted over said telephone circuit comprising meansrfortransmitting duplicate series of signals over said telephone circuit andover means independent of said telephone circuit, and means responsiveto differences be- Y tween said signals to sound an alarm.

2. In a telephone system, means for generating signals, a telephonecircuit, means for transmitting a series of said signals to saidtelephone circuit,`and means for testing the accuracy of said signals astransmitted over saidvtelep'hone circuit comprising means fortransmitting duplicate series of signals over said telephone circuit andover means independent of said telephone circuit, a receiving circuit,means for connecting said telephone circuit and said independent meansto said receiving circuit, and Vmeans in said receiving circuitresponsive to diiierences in said signals to sound an alarm.

3. In a telephone system, means for generating signals, a telephonecircuit, means for transmitting a series of said signals to saidtelephone circuit, and means for testing the accuracy of said signals astransmitted over said telephone circuit comprising means fortransmitting duplicate series of signals over said telephone circuit andover means independent of said telephone circuit, a receiving circuit,means for connecting said telephone circuit and said independent meansto said receiving circuit, means to count said signals, means normallyresponsive to the complete operation of said counting means to initiatefurther tests, and means in said receiving circuit responsive todifferences in said signals to disable said initiating means.

4. In a telephone system, means for generating signals, a telephonecircuit, means for transmitting a series of said signals to saidtelephone circuit, and means for testing the accuracy of said signals astransmitted over said telephone circuit comprising means fortransmitting ay duplicate series of signals over means independent Vofsaid telephone circuit, a receiving circuit,

means responsive to the transmission of the iirst of said series ofsignals to introduce signals from said telephone circuit and from saidindependent means into said receiving circuit in opposition, and meansresponsive to differences in said signais to sound an alarm. Y Y

Y5. In a telephone system, speech currents, a teiephone circuit, meansfor transmitting said speech currents to said telephone circuit, andmeans for testing the accuracy of said speech currents as transmittedover said telephone circuit comprising means for transmitting dupli-4tiate further operation cate speech currents over said telephonecircuit and over means independent of said telephone circuit, and meansresponsive to differences between said speech currents to sound analarm.

6. In a telephone system, means for generating speech currentscharacteristic of individual words, means for transmitting said wordsover a channel of known eiciency, means for transmitting said words overa channel of unknown efficiency, a receiving circuit, means forintroducing said words into said receiving circuit over said known andunknown channels in opposition, means for countingrthe number of saidwords, means responsive to said counting means to iniand means in saidreceiving circuit responsive to diierences in said words to disable saidinitiating means.

7. In a telephone system, a call announcing mechanism, a telephonecircuit, means for transmitting telephone designations from said callannouncing mechanism to said telephone circuit, and means for testingthe accuracy of said designations comprising means for transmittingduplicate designations over said telephone Vcircuit and over meansindependent of said telephone circuit, and means responsive todifferences between said designations to sound an alarm.`

8. In a telephone system, means for generating voice currentscharacteristic of the elements of telephone designations, a telephonecircuit, selective means for connecting said generating means to saidtelephone circuit to transmit a predetermined telephone designation, andmeans for testing the accuracy Yof said designation as transmitted,comprising duplicate selecting means having access to said generatingmeans, a receiving circuitmeans to introduce voice currents over saidtelephone circuit and over said duplicate selecting means into saidreceiving circuit in opposition, said receiving circuit responsive todifferences in said voice currents to sound an alarm. Y

9. In a telephone system, means for generating voice currentscharacteristic of individual words, a talking circuit, means fortransmitting said voice currents to said talking circuit, and means fortesting said voice currents as transmitted to said talking circuitcomprising a receiving circuit, means for connecting saidY talkingcircuit with said receiving circuit, means for transmitting said voicecurrents from said generating means to said receiving circuitindependent of said talking circuit and means under the control of saidreceiving circuitV for indicating whether or not said voice currentscoincide.

10. In a telephone system, means for generating voice currentscharacteristic of individual words, a talking circuit, means fortransmitting said voice currents to said talking circuit, and means fortesting said voice currents as transmitted to said talking circuitcomprising a receiving circuit, means for connecting said talkingcircuit with said receiving circuit, means for transmitting said voicecurrents from said generating means to said receiving circuitindependent of said talking circuit and means under the control of saidreceiving circuit for indicating whether or not said voice currentscoincide in character, intensity and duration. Y

ll. Inra telephone system, means Vfor generating voice currentscharacteristic of a plurality of individual words, a talking circuit,selective means for transmitting a series of said voice currents to saidtalking circuit, and means for testing said series of voice currents astransmitted to said talking circuit comprising a receiving circuit, andmeans connected with the secondary cuit, means for connecting saidtalking circuit Winding of said transformer responsive to differ- Withsaid receiving circuit, means for selectively ences in said voicecurrents to sound an alarm.

transmitting the same series of voice currents 14. In ka telephonesystem, senders including 12. In a telephone system, means forgeneratmeans for controlling the operation of said sending said seriesof voice currents as transmitted generating means have been selected. tosaid talking circuit comprising a receiving cirl5. In a telephonesystem, senders including cuit, means for connecting said talkingcircuit control circuits, a plurality of speech current from saidgenerating means to said receiving circontrol circuit, routine testingequipment comcurrents coincide in character, intensity and said controlcircuit, means to predetermine which spacing. speech generating meansshould be selected and 13. In a telephone system, means for generatmeansto test Whether said predetermined speech ing voice currentscharacteristic of the elements generating means have been selected, saidmeans of telephone designations, a telephone circuit, comprising atransformer having two primary said voice currents thereover, and meansto test under test to one primary Winding of the transthe voice currentsas transmitted over said teleformer, means independent of said senderfor phone circuit, comprising a transformer having connecting saidpredetermined generating means another, means for connecting currentfrom said and means connected with the secondary Windfor connectingcurrent from the same generating mary windings of said transformer tosound an mea-ns to the other primary Winding of said alarm. transformerindependent of said telephone cr- FRANK K. LOW.

